Wierd hissing noise....

[Jhop16]

Okay... So today I heard this really loud hissing noise comeing from the front end so i pulled over and me and my brother examined it for awhile, this is what we found..

1) It DOESNT do it in park... only in drive
2) The motor rocks alot when i put it drive from park..
3) The hissing goes away when we push down on the throttlebody, basically pushing the hole motor down...

ne1 able to help me out?? i have absolutly no clue, its not comeing from the intake or nething, the throttlebody was put on by a shop like 3 months ago, so idk how thatd be leaking nething...

[Cobalt Tom]

pop tb off, check gasket, resinstall. prob will go away

[mrsilent13]

sounds like a vacuum leak

[Jhop16]

that sucks, theres no way im touching the TB... last time i took it off i had to pay the assholes at a chevy dealership 400 bucks to put a new one on..

[mrsilent13]

wtf...why...ive pulled mine off so many times...why 400 bucks?

---------- Post added at 07:32 PM ---------- Previous post was at 07:31 PM ----------

its only 4 bolts...10mm bolts...take them off check the seal and if its bad go buy some or make your own seal with copper rtv

[DaBuzzard]

Originally Posted by mrsilent13 wtf...why...ive pulled mine off so many times...why 400 bucks? ---------- Post added at 07:32 PM ---------- Previous post was at 07:31 PM ---------- its only 4 bolts...10mm bolts...take them off check the seal and if its bad go buy some or make your own seal with copper rtv

IIRC, there was a bit of over zealous cleaning involved


The engine moving when you load it up like that is normal. It is trying to rotate the wheels but since the wheels aren't turning, the motor and trans are trying to rotate instead - they will move as far as the mounts will let them.
You don't want to see what's happening under the hood when you get a good wheel hop going - the top of the engine will slam (and I do mean SLAM) back and forth like it wants to escape

I would check farther back as well, maybe the downpipe has a bit of a leak that opens up when the engine moves in the cradle - not sure if pushing down on the tb would move it far enough back to "reseal" it though.

Vacuum leak I would expect to set a code....

[mrsilent13]

vacuum doesnt always set a code

---------- Post added at 12:48 AM ---------- Previous post was at 12:47 AM ----------

i had a vac leak for a while with no code

[DaBuzzard]

^^^ true, but if the leak is big enough to hear I would expect to see a long term fuel trim code set. Of course, it the leak is intermittent, it may not throw the ltft out enough to set a code.

Still suggest checking for a leak in the exhaust that is "opening up" when the drivetrain torques. Sounds can carry in funny ways under a car

[DaveBlank]

sorry, can't help

[mrsilent13]

Originally Posted by DaveBlank sorry, can't help

man you sig ir right on